The present invention relates to semiconductor devices, and more particularly to a TAB type ball grid array semiconductor device.
FIG. 1A is a plan view showing a conventional TAB type, FIG. 1B is a sectional view taken along the line 1B—1B of FIG. 1A. FIG. 1C is a sectional view taken along the line 1C—1C of FIG. 1A.
As shown in FIG. 1A through 1C, a Cu pattern 2 comprising copper (Cu) is formed on the surface of a polyimide tape (an insulating base) 1. The Cu pattern 2 is formed by allowing, for example, a copper foil to adhere to the polyimide tape 1, for example, with an adhesive agent and etching the Cu foil by using as a mask a resist layer having a pattern corresponding to, for example, the Cu pattern 2. On the surface of the polyimide tape 1, a solder resist layer 3 is formed, and this solder resist layer 3 is covered at least except for a wire bonding portion 2WB, and a ball pad portion 2BP.
On the rear surface of the polyimide tape 1, an adhesive agent layer 4 is formed. A protection tape 5 is allowed to adhere to the adhesive agent layer 4.
A semiconductor chip 6 is mounted on the TAB tape and is allowed to adhere to the TAB tape via the adhesive agent layer 4.
In allowing the semiconductor chip 6 to adhere to the TAB tape, as shown in FIG. 2A, the semiconductor chip 6 is picked up from the wafer-chip tray of the mounting device, and the semiconductor chip 6 is placed on a lower mold 22 of a pressurizing device.
Next, as shown in FIG. 2B, after the position of the TAB tape having the protection tape 5 peeled off and the position the semiconductor chip 6 is corrected, an upper mold 23 is allowed to come down so that the chip 6 is bonded onto the TAB tape.
However, with the conventional TAB tape, as shown in FIG. 1B, 1C or FIG. 2B, an uneven configuration is generated on the surface where the Cu pattern 2 is formed with the presence and absence of the Cu pattern 2. A concave portion 20 is a portion where no Cu pattern 2 is formed. A convex portion 21 is a portion where the Cu pattern 2 is formed.
Therefore, when the chip 6 is heat pressurized to the TAB tape, the pressure is concentrated on the convex portion 21 as shown in FIG. 2C with the result that the pressure is applied to the concave portion 22 with greater difficulty. A difference in this pressure distribution generates a difference in the adherence force between the TAB tape and the chip 6 which will lead to the peeling off of the TAB tape from the chip 6 later.
Furthermore, with the conventional TAB tape, as shown in FIG. 3A and FIG. 3B, there arises an intersection angle θ between the solder resist layer 3 and the wire bonding portion 2WB is less than 90 degrees.
Consequently, when the solder resist is printed on the TAB tape, a disuniformity is generated in the flow of the paste-like solder resist in the Cu pattern 2 particularly in the vicinity of the wire bonding portion 2WB, so that bubbles 24 are easily involved in the solder resist layer 3.
When bubbles are generated in the solder resist layer 3, and between the solder resist layer 3 and the polyimide tape 1. Water infiltrates into the bubbles from the outside so that the Cu pattern 2 is eroded with the lapse of time.